The present invention relates to a method of reducing the toxic components, more particularly nitrogen oxides, in the exhaust gas of internal combustion engines by returning a part of the exhaust gas to the intake side of the engine by means of an exhaust gas recycle line or conduit which is adapted to be controlled by a valve.
The recycling of exhaust gas is intended primarily to reduce the toxic NO.sub.x content when the engine is operating on partial load. 2 - 20% of exhaust gas relative to the quantity of fresh air drawn in by the engine is recycled. The valve controlling the exhaust gas recycle line is actuated as a function either of the underpressure in the induction tube or of the position of the throttle valve.